Many high-volume consumer products such as mobile devices and motor vehicles now include a digital camera. For example, FIG. 1 shows a mobile device 190 having a camera module 180 integrated therein. Camera module 180 includes an image sensor 102 beneath an imaging lens 170.
FIG. 2 is a cross-sectional view of a prior-art camera module 280, which is an example of camera module 180. Camera module 280 includes a lens barrel 200 bonded to image sensor 102, which includes a pixel array 104. Lens barrel 200 includes a cover glass 202, a lower spacer 204, a lens 270, an upper spacer 206, and a top cover glass 208. Lens 270 includes lens substrate 272, a bottom lens 274 and a top lens 276. Substrate 272 has a width 272W which equals a width 102W of image sensor 102.
Spacer 204 is typically formed of glass or plastic. Forming spacer 204 from glass is expensive, while a spacer 204 formed of plastic does not bond well with glass, e.g., of cover glass 202 or substrate 272, because of mismatched thermal expansion coefficients. Lens barrel 200 may include an opaque coating 271, located on the sensor-facing surface of substrate 272, for example, to prevent stray light from reaching image sensor 102.